The goal of this proposal is to extend our understanding of decision-making beyond the simple paradigms that have been studied thus far. Physiological recording and behavioral analysis will be used to describe how monkeys respond to more complex decision tasks;theoretical modeling will help interpret the responses. My training thus far makes me ideally suited for this endeavor: I have extensive experience in conducting physiology experiments in awake, behaving monkeys. Further, I have some experience in theoretical modeling;additional training will prepare me to make advances as an independent investigator. As a postdoctoral fellow, I have collected physiological data from monkeys engaged in a multiple choice decision task. This data has the potential to make a major advance to our understanding of decision making: the simplicity of previous tasks used to study decision-making suggests that they may offer limited insight into decision-making in general. Indeed, my data pose a major challenge to current models. The proposed career development plan incorporates training from my current mentor, Dr. Shadlen, on theoretical techniques to extend current models to explain more complex decisions. My co-mentors, Drs. Wang and Pouget, have agreed to enter into a collaboration to address this question. The collaboration will allow me to consider two novel models. The combined training from three mentors will provide a foundation in theoretical neuroscience that I can combine with my experimental skills as an independent researcher. For my independent research, I propose to combine my experimental and theoretical skills on a new series of experiments that further test more complex decisions. These experiments combine the visual decision-making task from my postdoctoral work with a novel, auditory decision-making task. The goals of this work are twofold: first, I will ask how the models of decision-making can be extended to incorporate input from 2 modalities. Next, I will ask how behavioral and physiological responses change when decisions are based on evidence from two modalities. A number of clinical disorders, foremost among them Autism, appear to cause impairments in the ability to integrate sensory information. Identifying neural mechanisms that underlie sensory integration within and across modalities may inform clinical treatments for Autistic patients.